The accuracy of target shooting and other instances of gun shooting is often related to the applicability, in the shooting environment, of the particular gun sight used. Often target and background illumination intensity vary greatly, making one style of gun sight become less useful, non-functional or even distracting as the lighting conditions change. It is therefore important that the shooter not only have a gun sight that is functional in moderate conditions and minimizes or eliminates related aiming and shooting problems such as cross-eye dominance, etc., but also function in both high or low illumination conditions and smoothly transition its operation as conditions change so as not to distract the shooter from the target or his style of target sighting.
Other changes of conditions or shooter gun sight preferences require that the gun sight, in addition to providing repeatable accuracy, be durable, removable and remountable without significant difficulty and be adaptable to gun type and dimensional variations. Previous gun sights often require permanent or semi-permanent mounting which requires special tooling or working to remove and accurately remount and align. In view of the many restrictions encountered with previously known gun sights, the marginal advantages by many gun sights are simply not worth the bother, requiring the shooter accommodate to the changes as best he can without changing the sight or having the sight respond to the changing conditions.